The advertising business has always had its share of arrangements that work better when no one looks at them too closely.
Principal media — the practice by which agency holding companies buy advertising inventory on their own account and resell it to clients at a markup — appears to be enjoying another moment in the sun, or perhaps more accurately, in the shade where it prefers to operate. Several industry observers say the major holding companies are pushing the practice more aggressively than ever, in part because they have not yet figured out how to charge for all the artificial intelligence tools they have been busily acquiring.
"One of the challenges with the agencies right now is that they don't know how to price and sell their technology," said Cyd Falkson, senior vice president of strategic accounts at the consultancy MediaSense. The holding companies, she added, are all looking for ways to "expand and grow margin and revenue from principal media."
(Problem, meet solution.)
The numbers suggest something is afoot. Omnicom's "third-party service costs" — a category that includes principal media transactions — reached nearly $2.9 billion in the first half of 2026, up from $1.7 billion in the same period a year earlier. That is not a rounding error.
Tom Denford, chief executive of the consultancy ID Comms, put it simply: "If we're seeing these things happening now, it's not a blip, it's a systemic shift."
The practice has its critics, who argue that an agency ceases to be an agent when it is also the seller. But Ms. Falkson noted that some of the loudest opponents simply lack the scale to compete. There may be, she suggested, "a sprinkling of envy mixed in with the righteous indignation."
For marketers, the choice increasingly resembles what the English cleric Thomas Hobson once offered customers at his stable: take this horse or take none at all.
Original story published in Digiday: "Principal media once again finds itself in headlines", by Michael Bürgi